In his 1880 essay, ‘The experimental novel’, Zola modelled literature on the physiological laboratory. The writer, he proposed, should experiment with his fictive subjects, manipulate their feelings and environments in order to grasp the laws of nature: ‘we should operate on the characters, the passions, on the human and social data … as the physiologist operates on living beings’. Zola drew extensively on Claude Bernard’s 1865 Introduction to the Study of Experimental Medicine, which described the central role of the laboratory for the production of scientific knowledge, the use of instruments to penetrate inside bodies and prise them apart, to intervene in the course of life, altering or destroying it. In this paper, I look first at the literature of physiology, how it was written, how it disciplined its readers, and how it stood in relation to other practices, especially those of the experimental laboratory with its transcription of living bodies by new precision machines. I then conclude with a reading of the novel, Heart and Science (1883) by Wilkie Collins, in which the physiological laboratory and the character of its practitioners were composed from the fragments of specialist physiology and recast as fiction using the methods of the experimenter. The novelist does indeed become a physiologist, manipulating the bodies of readers with the instrument of the text, revealing the Bernardian practices of the laboratory as a process in which human character is eroded and finally erased.